Question

the 3rd term of an ap is 3 and 11 to term is minus 21 find its first term and common difference

Answer 1

first term is 9 and difference is -3

Answer 2

T3=3=a+2d.......(1)
T11=-21=a+10d.........(2)
From eq 1 and 2,we have
d=-2
and a=7